The present invention relates to electrical connectors and particularly to a multi-row connector having a printed circuit ground plane board associated therewith for grounding the outer shields of conductors at the connector.
Many applications exist where it is necessary to transfer electrical signals representative of digital data and the like over several bundled wires from one device to another. Individual ones of these wires are usually shielded to isolate the data transmitted thereby from electromagnetic field disturbances caused by other data carrying wires, nearby power sources and the like. Crosstalk between one signal wire and another, which is particularly troublesome, also occurs at signal junction points, such as at connectors where an impedance mismatch is often formed.
A common prior art means for grounding the shields of several shielded wires which are to be terminated at a common pin of a multi-pin connector, is to solder or otherwise attach a short shield termination wire, called a pigtail wire, between adjacent shields. One of the shields is then connected by a pigtail wire to a common grounding pin on the connector.
The single grounding pigtail wire used in such a scheme has a high failure potential because of the strain placed upon it due to the bulkiness of the several shielded wires which it anchors. Should the single ground wire fail, all of the shield grounds are lost. Moreover, should an additional shielded wire be added to the group, or removed from the group, one of the series-connected shield terminations may have to be modified or reworked. In addition, the daisy-chaining of pigtail wires creates an effective antenna for inducing unwanted signals or noise into the wires.
U.S. Pat. No. 3,513,433 issued to Charles E. Carroll on May 19, 1970 recognizes the problems mentioned above and provides one solution therefor. The solution presented in this patent consists of the addition to the connector of a grounding bracket having a bar which spans the length of the connector. The bar is positioned exterior of the connector shell and has base portions, or legs, which attach to the shell. All of the shielded wires have their shield termination pigtail wires soldered to the bar.
While the aforementioned solution does eliminate some of the problems associated with the daisy-chain grounding configuration adopted earlier, it still requires that individual grounding wires or pigtails be attached to the individual shielded wires. This is a costly and time consuming operation.
U.S. Pat. No. 4,232,929 issued to Franz Zobawa on Nov. 11, 1980, provides a solution to the crosstalk problem associated with the coupling of several data signals to a common multi-row connector. A spring clamped shield or plate is inserted between one row of pins which forms a signal plane and an adjacent row of pins which forms a ground plane. The shield contacts all of the pins of the ground plane. It is stated that the concentration of the electrical field in the vicinity of the shield plate results in an overall reduction in crosstalk from one pin of the signal plane to another.
While this patent teaches a partial solution to the crosstalk problem applicable to a particular connector configuration, it does not teach any means for securing and grounding the ends of shielded wires, and appears to address itself to so-called stranded spiral quads in which two conductors arranged opposite one another serve as signal conductors and the other two conductors as ground conductors.